Liquid heating apparatus and control system therefor



an- 3, 1961 P. F. SWENSON mm. 2,967,021

LIQUID HEATING APPARATUS AND CONTROL SYSTEM THEREFOR Filed May 9, 1958 Rm m m LIQUID HEATING APPARATUS AND CONTROL SYSTEM THEREFOR Paul F.Swenson, Cleveland Heights, and Myron T.

'Cooperrider, Cleveland, Ohio, assignors to Iron Fireman ManufacturingCo., Cleveland, Ohio, a corporation of Oregon Filed May 9, 1958, Ser.No. 734,336

Claims. (Cl. 2361) This invention relates to a new and improved liquidheating apparatus and particularly to an automatic control systemtherefore, and is an improvement in the iuvention disclosed in thecopending application to Paul F. Swenson and Myron T. Cooperrider,Serial No. 347,048, filed April 6, 1953, now Patent.No. 2,836,365,entitled Steam Generating Apparatus and Controls Therefor.

In the apparatus described in the above-identified c0- pendingapplication, a continuously burning pilot uncontrolled by the controlsystem is employed. The present invention is a modification of theearlier control system by virtue of which the pilot burner itself alsois under the control of the thermostatically controlled valve so that,in event of failure of the control valve or the fluid pressure operatingmeans therefor, the pilot will be extinguished along with the mainburner.

Heretofore, in hot water heaters, boilers, furnaces, and the like, ofthis character, the danger of gas explosions due to the continuoussupply of gas to the pilot was very remote.

The ordinary illuminating gas customarily used was lighter than air andconsequently the small amount of gas supplied to an extinguished pilotwould be vented through the usual stack, or if not vented through thestack, would rise in the air and generally leak out of the house withthe air at a rate sufficiently great so that the accumulation of anyappreciable amount of the illuminating gas or gas and air mixturesufficient to cause explosions was very remote. More recently, however,the gas supplied for water heaters and the like is a liquid petroleumgas which is supplied in tanks usually located on the ground leveloutside of the house and connected to the feed line system in the housethrough a throttling valve.

This petroleum gas is heavier than air and consequently, if the pilotbecomes extinguished, the escaping petroleum gas tends to settle to thefloor level. Since such heaters are usually located in the basement,there is little chance for the gas to escape. Ordinarily, sewer anddrain outlets are provided with gooseneck traps which, of course, form abarrier. As a result, the gas will accumulate in the basement to a levelwhich might be from a few inches to several feet. Unless it isaccumulated to a considerable elevation so that a person walking in thebasement Will cause drafts and eddy currents which will carry the gasupwardly so that it can be detected by its odor, there is a grave dangerthat a person will unwittingly light a match to relight the burner and,

when the flame is moved to the level of the pilot burner,

- will ignite the large accumulation of the gas or gas-air mixture inthe basement. Accordingly, therefore, it is becoming increasinglynecessary that some means be provided for stopping the supply of gas tothe pilot in event the pilot becomes extinguished and cannot bereignited immediately by the main burner if the latter happens to beoperating. 1

In accordance with the present invention, the control of the abovecopending application is modified so that nited States Patent 02,967,021 Patented Jan. 3, 1961 ice it is necessary for igniting thepilot in the first instance to operate a manual valve, but after thepilot is ignited, the supply of fuel thereto is maintained independentlyof the manual valve so long as the pilot is operating, but isdiscontinued if the pilot remains inoperative for a very short interval.This is accomplished while retaining the control features of the earlierinvention.

Various other objects and advantages of the present invention willbecome apparent from the following description wherein reference is madeto the drawing, in which the drawing is a fragmentary, vertical,sectional view through a heating apparatus and control embodying theprinciples of the present invention, parts thereof being shown inelevation for clearness in illustration.

Referring to the drawing, the invention is shown in combination with asteam generating system which employs a boiler 1 to which a heating coil2 is connected, the steam from the heating coil 2 entering the boiler 1through a conduit 3 which opens above the normal level L of the water inthe boiler. A recirculating line 5 leads to the lower end of the coil 2.

In order to heat the coil 2, a suitable main burner 6 is provided.Adjacent the burner 6 is a pilot burner 7 in mutual firing relationthereto. Gas is supplied to the main burner 6 through a suitable gasline 8 and is supplied to the pilot 7 through suitable lines 9 and 10,as will be more fully described hereinafter. The pilot 7 is arranged inheating relation to a bulb 11 of a sealed expansible fluid type ofthermostatic device. The bulb 11 is continuously connected by a duct 12to a bellows 13 and is operative so that, upon heating of the bulb, the

bellows is expanded. In the tank 1, below the liquid level therein so asto be subjected to the heat of the water, is another bulb 14 of the typesimilar to the bulb 11. The bulb 14 is connected by the duct 15 to thebellows 13 also so that, upon expansion of the fluid in the bulb 14, thebellows is expanded.

The bellows comprises part of a thermostatic valve device indicatedgenerally at 16, into which gas is supplied through a suitable feed line17. The duct 10, leading to the pilot, is connected to the feed line 17in advance of the valve device 16. A suitable manual valve 18 isinterposed in the line 10 between the feed line 17 and the pilot 7. Thevalve 18 is provided with a valve plug 19 which is held in normallyseated condition by a spring 20 acting through a rod 21. Rod 21, inturn, is provided with a push button 22 which can be depressed manuallyadmitting fuel to the main burner.

As more fully described in our copending application, one end of thebellows 13 is held in fixed position relative to the body 23 of thevalve device 16. The other end of the bellows is fixedly connected to arod 24, the opposite end of which is connected to a spring 25 adjustableby a suitable screw 26 for increasing and decreasing its tension. Thespring 25 is arranged to apply tension to the rod 24 so as to urge thebellows in the expanding direction.

Mounted .in surrounding relation to the rod 24 is a sleeve 27 which, atone end, abuts the free end wall of the bellows 13 but is unconnectedthereto and is freely movable endwise of the rod 24 and relative to thebellows. Mounted on the rod 24 is an adjustable abutment 28 betweenwhich and the lower end of the sleeve 27 is interposed a light spring 29which yieldably holds the sleeve 27 in a position with its end inabutment with the end of the bellows 13. Mounted on the sleeve 27 is avalve plug 30 which is movable with the sleeve, and thus, in the formillustrated, is moved downwardly upon expansion of the bellows 13 byexpansion of the fluid in the bulbsll and'14. The valve device 16 isprovided with a pair of spaced seats 31 and 32 which are coaxial witheachother and are spaced apart axially. The seat 31 is the inlet seatand the seat 32 is the outlet seat, so-that fuel supplied through theline 17 passes first through the port of the seat 31 thence through theport of the seat 32 to the main burner supply line 8. The plug 30 ismounted on the sleeve 27 between the seats. The spacing of the seats andthe size of the plug 30 are such that when the pilot burner is oif sothat the fluid in the bulb 11 is unheated, the bellows will besufficiently contracted so that the plug 30 will seat on the inlet seat31 and thus stop the supply of gas to the burner 6. On the other hand,it will open to admit gas through the Port of the seat 31 and to andthrough the port of the seat 32 when the bulb 11. is heated sutficientlyto expand the fluid therein. Thus lighting of the pilot results inintroduction of the gas to the main burner 6 around the plug 30.However, as described in the above copending application, it is desiredto reduce the flow of gas to the burner 6 through the line 8 if thetemperature in the tank reaches a predetermined maximum. As thistemperature approaches the maximum, the fluid in the bulb 14 expands andfurther expands the bellows, thus moving the plug 30 from theintermediate position between the seats toward the seat 32. The plug,however, is not moved to the seat 32 but remains between the seats sothat fuel is continuously supplied to the main burner 6. As thetemperature further increases and heats the bulb 14, the bellows expandsfarther and moves the sleeve 27, and with it the plug 30, downwardly,closer to the seat 32, thus gradually reducing the flow of gas to themain burner.

The valve plug 311/ is arranged to be seated on the seat 32 with a snapaction. For this purpose, a magnet 33 is mounted in the body 23 foradjustment endwise of the sleeve 27 toward and away from the lower endof the sleeve 27. The magnet is connected to an adjusting screw 34 sothat it can be adjusted to preselected positions endwise of the sleeve.The sleeve 27 is magnetic, or at its lower end contains magneticmaterial, so as to be responsive to the magnet when it approachesclosely enough thereto.

When the temperature in the tank, and hence of the. bulb 14, reaches apredetermined maximum value, the.

pressure developed by the bulb 14, added to that of the bulb 11, andassisted by the spring 25, further expands the bellows sufliciently tomove the lower end of the sleeve into such close proximity of the magnet33 that the magnet pulls the sleeve 27 downwardly, overcoming the spring29, and seats the plug 30 on the seat 32 with a snap-action.

The duct 9 for maintaining the pilot continuously in operation isconnected to the interior of the body 23 at a location between the seats31 and 32. Accordingly, after the pilot is ignited by gas suppliedthrough the duct 10 and'the manually operable valve 18 and heats thebulb 11 sufliciently to lower the plug 30 from the seat 31, the pilot'ismaintained thereafter by gas supplied through the inlet port of the seat31 and the duct 9. It is to be noted that both the ducts 9 and 10 leadto the pilot and each discharges into the atmosphere in the pilot tubethrough its individual duct so that the ducts 9 and 10 are isolatedfrplm each other and gas cannot flow from one into the ot er.

Thus, in operation, should the pilot light become extinguished and notimmediately reignited by the main burner, then the plug '30 will bemoved into seating relation to the seat 31, thus stopping the supply ofgas both to the main burner and to the pilot. If, of course, the mainburner happens to remain ignited when the pilot is extinguished, thepilot is immediately reignited, by the main burner.

If desired, the valve plug 30 may be secured to the sleeve for slightrocking movement as described in the copending application aboveidentified, but it is held in fixed position-relative to the sleeve 27endwise or axially of the sleeve.

Upon full contraction of the bellows 13, the spring 25 is overcome byvirtue of the pull on the rod 24 so that the seating spring 29 isoperative for lifting the sleeve 27 and plug 30 to cause the plug '30 toseat on the seat 31.

Further, if desired, the duct 9 which supplies the pilot may beconnected to the pilot through a suitable cutoff valve 35 which isoperated by a push button 35a and floatoperated lever 36. A float 37,for operating the lever 36, is provided. The float also operates anormal water supply valve 38 in a water supply line 39, for admittingreplacement water to the boiler 1, when the water level falls too low.The float is arranged within the boiler 1 and is operative when thelevel of the-water in the boiler is reduced beyond a predeterminedminimum to operate the button 35a and close the valve 35, thus cuttingoff the pilot, whereupon the control valve device operates to stop thesupply of fuel to both the pilot and the main burner.

In this manner, the dangers of overheating, due to low water in theboiler, are eliminated.

In order that the device fail safe in event a leak occurs in the bulband bellows system while the pilot is extinguished, the bellows and bulbsystem used is preferably one in which the internal pressure, when thesystem is originally charged and sealed, is sub-atmospheric and soremains until predetermined heating of the bulbs and expansion of thefluid develops a positive pressure therein. The contractive force of thebellows, tending to lift the valve plug 30,. is due to the inherentresilient resistance of the bellows to elongation and the resultantself-restoring force, plus the sub-atmospheric pressure in the system.

The spring 25 is made adjustable in tension to vary the temperature atwhich the valve is opened and closed by the bellows, but so that in alladjusted conditions of operation it has suflicient tension to overcomethe inherent resistance to elongation of the bellows alone, when thebellows is unrestrained by sub-atmospheric pressure in the lines 12 and15, to a degree necessary to move the lower end of the sleeve closeenough to the magnet to cause the magnet to snap the plug 30 into closedseated position on the seat 32.

Consequently, should a leak occur in the bulb and bellows. system sothat only the inherent self-restoring force of the bellows resists theexpansion of the bellows by the spring 25, the spring 25' will move thesleeve sufliciently close to the magnet 33 so that the magnet will seatthe plug 30 on the seat'32 and thus cut ofi the supply of fuel to themain burner.

However, should the pilot be, or become, extinguished during the failurecaused by a leak in the bulb and bellows system, fuel would stillpass-to the pilot through the seat 31, except for the fail safe now tobe described.

When the lower end of the sleeve 27 is moved by the spring 25closeenough to the magnet 33 so that the sleeve comes under the influence ofthe magnet and is drawn, with a snap action, toward and by the magnet,the upper end of the sleeve is moved downwardly away from the lower endof the bellows 13, thus establishing a clearance space between the lowerend of the bellows 13 and the upper end of the sleeve 27. Thus, in eventa leak develops in the bulb and bellows system so that thesubatmospheric pressure'is relieved, the spring 25 can elongate the'bellows additionally even though the plug 30 is seated on the seat 32.Since there is a leak in the system, the spring 25 continues elongatingthe bellows in a direction to reduce the clearance between the upper endof the sleeve 27 and lower end of the bellows 13. Normally, this actionwould continue until the bellows were again engaged with the upper endof the sleeve, at which point. further movement would be arrested due tothe valve plug 30' being seated on the seat 32.

To render the system fail safe under such conditions, therefore, a valveplug 40 is fixedly connected to the bottom of the bellows for movementtherewith. The plug 40 is preferably of somewhat greater diameter thanthe plug 30 and the ports of the seats 31 and 32 so that, even though itis only slightly open, a relatively large annular passage for gas isprovided between it and the seat 31. The lower edge or seating area ofthe valve plug 40 is positioned axially of the seats so that it canengage and seal on the seat 31 before the clearance between the lowerend of the bellows 13 and the upper end of the sleeve 27, when thesleeve 27 is held by the magnet 33 in the downward position with thevalve 30 seated on the seat 32, is eliminated. Accordingly, therefore, aleak in the fluid pressure system, resulting in failure of itsoperation, causes a closure of the valve plug 40 on the top of the seat31 and stops the flow of fuel to the pilot as well as to the mainburner.

It is apparent from the foregoing description that the device is onewhich is arranged to fail-safe in all instances and furthermore, uponfailure of the system for any reason or upon extinguishing the pilotwithout its immediate reignition, not only is the supply of fuel to themain burner discontinued, but also the supply of fuel to the pilot isdiscontinued, thus eliminating the very serious explosive hazard due tothe use of heavier than air fuels.

It is to be noted that, in the case of fuel oils, this hazard stillexists as fuel oil escaping in a basement can cause fumes which canbecome explosive.

Further, it is to be noted that these hazards are increasing due to thefact that quite often automatic and other furnaces are provided which,at any time, may cause ignition of the accumulated gases.

Having thus described our invention, we claim:

1. A fluid fuel control valve for controlling the flow of fuel to aheating apparatus containing a liquid to be heated and having a main anda pilot burner, said valve comprising a housing with a fluid fuel inletport adapted to be connected to an associated fuel source and a fluidfuel outlet port connected to the main burner, said housing containingan annular inlet seat and an annular outlet seat coaxial with said inletseat and spaced therefrom in a direction nearer the valve outlet port inthe direction of flow of fluid through the valve from its inlet port toits outlet port, a fluid motor means disposed above said inlet seat andhaving a movable wall displaceable toward and .away from the inlet seatin response to pressure changes interiorly of the motor means,thermo-responsive bulb elements adapted to be disposed in heatassociation with the pilot burner and with the liquid to be heated,means forming a confined fluid column respectively connecting said bulbelements, said bulb elements and confined columns being initiallycharged and sealed with a thermo-responsive fluid at sub-atmosphericpressure whereby subsequent vapor pressure developed in both of the bulbelements by heating the elements is transmitted by the confined columnsto the interior of the motor means, a pilot duct adapted to connect theinterior of the valve at a location between the seats with the pilotburner, a pilot by-pass duct adapted to connect the pilot burner withthe associated fuel source, a normally closed valve in the by-pass ductand operable to be opened for admitting fluid fuel to the pilot burner,a rod secured to said movable wall for movement therewith and extendingthrough and beyond said seats, a sleeve member slidably telescoped ontosaid rod with the upper end of the sleeve disposed immediately adjacentsaid wall and movable axially relative thereto, a valve plug secured onsaid sleeve at a point intermediate the seats, said valve plug beingmovable with the sleeve in opposite directions for fluid sealingcooperation with the seats, respectively, resilient means compressionconnected to the lower end of the sleeve for urging said sleeve towardsaid wall in a manner to normally seat the valve plug on the inlet seatwhen pressure is not being supplied to the motor means by the bulbelements, supplemental valve closing means disposed at a, preselecteddistance below the lower end of the sleeve and operable upon apredetermined approach of the valve plug toward the outlet seat to movethe sleeve relative to, and away from, the motor means, and thereby tomove the valve plug into seating relation with the outlet seat againstthe force of said resilient means, whereby the upper end of the sleeveis spaced from said wall and the motor means may expand further, and asafety valve plug secured to the lower side of said wall and movablewith the wall toward and into seating relation with the inlet seat uponsaid further expansion of the motor means after the first-named valveplug is seated on the outlet seat.

2. A fluid control valve according to claim 1 wherein the pilot by-passduct is uncommunicated with the pilot duct between said valve housingand the point of connection of the pilot duct with the pilot burner.

3. A fluid control valve according to claim 1 wherein said fluid motormeans is a pressure-responsive bellows axially elongatable in responseto pressures applied interiorly thereof.

4. A fluid control valve according to claim 1 having a second resilientmeans tensionally secured to the lower end of said rod for supplementingthe expanding action of the motor means.

5. A fluid control valve according to claim 1 wherein said supplementalvalve closing means is a permanent magnet rigidly disposed below thelower end of the sleeve for drawing the sleeve downwardly out of contactwith the said wall with a snap action and thereby sealingly seating thefirst-mentioned valve plug on the outlet seat.

References Cited in the file of this patent UNITED STATES PATENTS

